Synthesis and Magnetic Properties in Quaternary Ca1-xPrxCo2As2 Single Crystals.

Series of Ca1-xPrxCo2As2 (x = 0, 0.10, 0.25, 0.4, 0.6, 0.75, 0.85, 1) single crystals have been synthesized in order to clarify the variation of magnetic order from antiferromagnetic in CaCo2As2 to ferromagnetic in PrCo2As2. It is found that the lattice constant of c-axis are contracted with the introduction of Pr into Ca sites in CaCo2As2. Electronic transport measurements reveal the metallicity in this system. Systematic magnetic measurements and analysis show that substituting only 10% of Pr for Ca changes the magnetic ground state from A-type antiferromagnetic ordering of Co magnetic moment in CaCo2As2 to ferromagnetic ordering in Ca1-xPrxCo2As2 (0.1≤x≤1). Most importantly, the abrupt drop of low temperature magnetic susceptibility below TFiM with x≥0.25 and the observed magnetic pole reversal with x≥0.4 suggests an antiferromagnetic coupling between Co 3d and Pr 4f magnetic sublattice. Finally, a detailed magnetic phase diagram in this system has been obtained.